Air-assist flare

ABSTRACT

An air-assist flare includes a flare body, a gas feed pipe, and a pilot burner. The flare body includes a tubular body having a longitudinal axis and a fan adjacent to a proximal end of the tubular body. The fan is configured to drive a flow of air through the tubular body along the longitudinal axis. The gas feed pipe includes an output port within the tubular body. The pilot burner is configured to ignite a mixture of flammable gas discharged through the output port and the flow of air. The gas feed pipe supports at least a portion of the weight of the flare body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit U.S. Provisional Application Ser. No. 61/989,256, filed May 6, 2014 under 35 U.S.C. §119(e). The above-referenced application is incorporated herein by reference in its entirety.

BACKGROUND

Gas flares are combustible gas burners that are commonly used in industrial plants, such as petroleum refineries, chemical plants, natural gas processing plants, as well as oil and gas production sites. A typical flare apparatus includes a flare stack, which can extend high above the ground, and a flare tip mounted on the flare stack.

In an air-assist flare, one or more blowers are used to blow air up through the flare stack. The air-assist flare is generally useful with tanks or other low-pressure sources (e.g., 8 oz. of tank pressure). The fan allows the flare tip to draw a sufficient flow of gas and air to cleanly burn the gas.

SUMMARY

Embodiments of the invention are generally directed to an air-assist flare for use in burning waste gases and an air-assist flare system. In some embodiments, the air-assist flare includes a flare body, a gas feed pipe, and a pilot burner. The flare body includes a tubular body having a longitudinal axis and a fan adjacent to a proximal end of the tubular body. The fan is configured to drive a flow of air through the tubular body along the longitudinal axis. The gas feed pipe includes an output port within the tubular body. The pilot burner is configured to ignite a mixture of flammable gas discharged through the output port and the flow of air. In some embodiments, the gas feed pipe supports at least a portion of the weight of the flare body.

Some embodiments of the air-assist flare system include an air assist flare, a main pipe, a source of waste gas, a source of pilot gas, an ignition controller, and a fan controller. The air assist flare includes a flare body, a gas feed pipe, and a pilot burner. The flare body includes a tubular body having a longitudinal axis and a fan adjacent to a proximal end of the tubular body. The fan is configured to drive a flow of air through the tubular body along the longitudinal axis. The gas feed pipe includes a proximal end attached to a distal end of the main pipe, and a distal end within the tubular body having an output port. The pilot burner is coupled to the source of pilot gas and is configured to ignite a mixture of flammable gas discharged through the output port and the flow of air. The ignition controller is configured to trigger ignition of the pilot gas output through the pilot burner. The fan controller is configured to control the fan. In some embodiments, the gas feed pipe supports at least a portion of the weight of the flare body.

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the Background.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified diagram of an air-assist flare system in accordance with exemplary embodiments of the invention.

FIG. 2 is an isometric view of an air-assist flare in accordance with exemplary embodiments of the invention.

FIGS. 3-6 respectively are right side, left side, front side, and back side views of the air-assist flare of FIG. 2, in accordance with exemplary embodiments of the invention.

FIG. 7 is a side cross-sectional view of the air-assist flare of FIG. 2, taken generally along line 7-7.

FIGS. 8 and 9 respectively are top and bottom views of the air-assist flare of FIG. 2, in accordance with exemplary embodiments of the invention.

FIG. 10 is an isometric exploded view of components of the air-assist flare in accordance with embodiments of the invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Embodiments of the invention are described more fully hereinafter with reference to the accompanying drawings. Elements that are identified using the same or similar reference characters refer to the same or similar elements. The various embodiments of the invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

Specific details are given in the following description to provide a thorough understanding of the embodiments. However, it is understood by those of ordinary skill in the art that the embodiments may be practiced without these specific details. For example, circuits, systems, networks, processes, frames, supports, connectors, motors, processors, and other components may not be shown, or shown in block diagram form in order to not obscure the embodiments in unnecessary detail.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, if an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Thus, a first element could be termed a second element without departing from the teachings of the present invention.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Embodiments of the invention may also be described using flowchart illustrations and block diagrams. Although a flowchart may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be re-arranged. A process is terminated when its operations are completed, but could have additional steps not included in a figure or described herein.

As will further be appreciated by one of skill in the art, the present invention may be embodied as methods, systems, devices, and/or computer program products, for example. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. The computer program or software aspect of the present invention may comprise computer readable instructions or code stored in a computer readable medium or memory. Execution of the program instructions by one or more processors (e.g., central processing unit) results in the one or more processors performing one or more functions or method steps described herein. Any suitable patent subject matter eligible computer readable media or memory may be utilized including, for example, hard disks, CD-ROMs, optical storage devices, or magnetic storage devices. Such computer readable media or memory do not include transitory waves or signals.

The computer-usable or computer-readable medium may be, for example but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, and a portable compact disc read-only memory (CD-ROM). Note that the computer-usable or computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via, for instance, optical scanning of the paper or other medium, then compiled, interpreted, or otherwise processed in a suitable manner, if necessary, and then stored in a computer memory.

It is understood that one or more of the blocks (of the flowcharts and block diagrams) may be implemented by computer program instructions. These program instructions may be provided to a processor circuit, such as a microprocessor, microcontroller or other processor, which executes the instructions to implement the functions specified in the block or blocks through a series of operational steps to be performed by the processor(s) and corresponding hardware components.

FIG. 1 is a simplified diagram of an air-assist flare system 100 that includes an air-assist flare or combustible gas burner 102, in accordance with exemplary embodiments of the invention. The system 100 is generally configured to burn waste gas from a waste gas source 104. Exemplary embodiments of the waste gas source 104 include a gas source of a petroleum refinery, a chemical plant, a natural gas processing plant, an oil and/or gas production site, or other gas source. In some embodiments, the waste gas source 104 contains flammable gas at a relatively low-pressure, such as in a tank.

In some embodiments, the air-assist flare 102 includes a flare body 106, a gas feed pipe 108, and a pilot burner 110. In some embodiments, the flare body 106 includes a tubular body 112 having a longitudinal axis 114. The tubular body 112 is formed of stainless steel, or other suitable material.

In some embodiments, the flare body 106 includes a fan 116 adjacent a proximal end of the flare body 106, such as a proximal end 118 of the tubular body 112. In some embodiments, the fan 116 is supported by the tubular body 112. In some embodiments, the fan 116 is attached to the proximal end 118 of the tubular body 112 (FIG. 1), or is supported within the proximal end 118 of the tubular body 112.

A distal end 120 of the gas feed pipe 108 extends into the tubular body 112, as shown in FIG. 1. An output port 122 at the distal end 120 discharges flammable or combustible gas 124 received from the waste gas source 104. In some embodiments, a proximal end 123 of the gas feed pipe 108 is coupled to a distal end 125 of a main pipe 126, which is coupled to the gas source 114. Thus, the flammable gas 124 is delivered from the source 104 through the main pipe 126 and the gas feed pipe 108, and is discharged through the output port 122. In some embodiments, the pipes 108 and 126 are formed of stainless steel or suitable material.

The pilot burner 110 is configured to ignite the gas 124 discharged through the output port 122. In some embodiments, the pilot burner 110 receives a flow of combustible pilot gas from a pilot gas source 130, and an ignition controller 132 controls the ignition of discharged pilot gas 124. In some embodiments, the ignition controller 132 includes one or more processors configured to execute instructions stored in memory to control the operation of the pilot burner 110. In some embodiments, the ignition controller 132 is remotely located from the air-assist flare 102, and controls the ignition of the pilot gas through an insulated conductor 134. In some embodiments, the ignition controller 132 controls the flow of the pilot gas from the gas source 130 to the pilot burner 110. In some embodiments, the air-assist flare 102 includes at least one sensor 135 (FIG. 1), and the ignition controller 132 controls the ignition of the pilot burner 110 based on a signal from the sensor 135. In some embodiments, the sensor 135 is a temperature sensor (e.g., thermocouple), which may be located within the flare body 106 (FIG. 1) or external to the flare body 106, and the ignition controller 132 controls the ignition of the pilot burner 110 based on a temperature signal from the sensor 135.

The fan 116 of the air-assist flare 102 is configured to pull air that is external to the bottom or proximal end 138 of the flare body 106 and drive a flow of air 140 along the longitudinal axis 114 and through the tubular body 112, as illustrated in FIG. 1. In some embodiments, the fan 116 includes a direct current (DC) motor 142 to drive rotation of the blades of the fan 116. Additionally, in some embodiments, the fan motor is a relatively low power motor as compared to the large air-assist flares that require high power alternating current (AC) motors for their fans due to the need to drive a larger volume of air through the stack, as opposed to the relatively small volume of air that must be driven through the air-assist flare 102 in accordance with some embodiments of the invention. The use of the DC motor 142 simplifies the power and controls required by the system.

In some embodiments, the fan 116 has a diameter 144 that is larger than the diameter 146 of the tubular body 112. In some embodiments, the fan 116 may have a diameter of 10 or more inches, such as 12 inches, and the tubular body 112 may have a diameter of less than 10 inches, such as 8 inches, for example.

In some embodiments, a fan controller 146 controls the operation of the fan 116. In some embodiments, the fan controller 146 includes one or more processors configured to execute instructions stored in memory to control the operation of the fan 116. In some embodiments, the fan controller 146 may be combined with the ignition controller 132 into a single system controller. In some embodiments, the fan controller 146 is remotely located from the air-assist flare 102, and controls the operation of the fan 116 through an insulated cable 148.

In some embodiments, the fan 116 has a variable speed, which is controlled by the controller 146 to adjust the speed of the airflow 140. In some embodiments, the fan controller 146 receives a signal output from at least one sensor, such as the sensor 135 of the air-assist flare, or a sensor 149 in the waste gas source, and controls the speed of the fan 116 based on one or more signals from the sensor 135 and/or the sensor 136. In some embodiments, the sensor 135 is a temperature sensor configured to output a temperature signal indicative of a temperature associated with the air assist flare 102, and/or flow sensor configured to output a flow rate signal indicative of a gas flow rate within the tubular body 112, and the fan controller 146 controls the speed of the fan 116 based on the temperature signal and/or the flow rate signal. In some embodiments, the sensor 149 is a pressure sensor that is configured to output a pressure signal indicative of a pressure within the waste gas source, such as a tank, and the fan controller 146 controls the speed of the fan 116 based on the pressure signal. In some embodiments, the fan controller 146 controls the operation of the fan 116 based on a signal from the ignition controller 132.

In operation, gas 124 is discharged through the output port 122 of the gas feed pipe and into the interior of the flare body 106, such as adjacent a distal end 150, for example. The fan 116 drives the airflow 140 to pull air that is external to the air-assist flare 102 through the proximal end 138 and the interior of the flare body 106. The airflow 140 mixes with the gas 124 and is ignited by the pilot burner 110 and the resultant flame extends out the distal end 150. This results in the burning of the waste gas 124.

In some embodiments, the air-assist flare 102 is formed much smaller than traditional air-assist flares. For instance, in some embodiments, the flare body 106 has a length 151 of less than 8 feet, less than 6 feet, or less than 4 feet. In some embodiments, the length 151 is less than 8 feet, such as 2-8 feet, 2-6 feet, 2-4 feet, 4-6 feet, or 5-8 feet. Accordingly, the air-assist flare 102 is significantly smaller and lighter than traditional air-assist flares, which typically have a length of 10-20 feet.

The relatively small size of the air-assist flare 102 makes it suitable for burning smaller volumes of combustible gas than traditional air-assist flares, such as approximately 130,000 cubic feet per day. In order to increase burning capacity, multiple air-assist flares 102 may be coupled to the same source 104 of the flammable waste gas. In some embodiments, multiple air-assist flares 102 are coupled to the same pipe 126 or separate pipes that are coupled to the waste gas source 104. Accordingly, one may customize an arrangement of air-assist flares 102 to accommodate a volume of combustible gas that is to be burned, thereby avoiding the necessity of using an air-assist flare that is larger and more expensive than necessary for the job. Additionally, the smaller size and lower cost of the air-assist flare 102 justifies its use for low-volume applications over non-air-assist type flares having lower burning efficiencies.

In some embodiments, the air-assist flare 102 is much lighter than conventional air-assist flares. In some embodiments, the air-assist flare 102 or the flare body 106 weighs less than 180 pounds, such as in the range of 140-180 pounds, for example. The relatively light weight of the air-assist flare 102, allows for unique mounting arrangements. In some embodiments, the air-assist flare 102 is substantially supported on the gas feed pipe 108 and/or the pipe 126, as shown in FIG. 1. In some embodiments, at least a portion of the weight of the flare body 106 is supported by the gas feed pipe 108 and/or the pipe 126. In some embodiments, at least 90%, 95% or 100% of the weight of the flare body 106 is supported by the gas feed pipe 108 and/or the pipe 126.

In some embodiments, the main pipe 126 has a large diameter relative to the gas feed pipe 108. In some embodiments, the main pipe 126 has a diameter in the range of 6-10 inches, such as 8 inches. In some embodiments, the gas feed pipe 108 has a diameter in the range of 1.5-3.0 inches, such as 2.0 inches, for example.

In some embodiments, a coupling 152 joins the pipe 108 to the output of the pipe 126. In some embodiments, the coupling 152 includes a tapered section 154, which transitions the diameter of the conduit from that of the main pipe 126 to that of the gas feed pipe 108.

In some embodiments, the coupling 152 between the pipe 108 and the pipe 126, includes a flange 155 that mates with a flange 156 of the pipe 126. The flanges 155 and 156 may be coupled together using conventional techniques, such as using nuts and bolts, or other suitable fastening techniques.

Additional embodiments of the invention will be described with reference to FIGS. 2-10. FIG. 2 is an isometric view of an air-assist flare in accordance with exemplary embodiments of the invention. FIGS. 3-6 respectively are right side, left side, front side and back side views of the air-assist flare of FIG. 2, in accordance with exemplary embodiments of the invention. FIG. 7 is a side cross-sectional view of the air-assist flare of FIG. 2, taken generally along line 7-7 of FIG. 2. FIGS. 8 and 9 respectively are top and bottom views of the air-assist flare of FIG. 2, in accordance with exemplary embodiments of the invention. FIG. 10 is an isometric exploded view of components of the air-assist flare in accordance with embodiments of the invention. Elements in the figures that are identified by the same or similar reference number correspond to the same or similar elements.

In some embodiments, the fan 116 is coupled to the proximal end 118 of the tubular body 112 through a conical section or cone 160 that surrounds the fan 116, as shown in FIGS. 1-7. In some embodiments, the bottom or proximal end 118 of the tubular body 112 includes a flange 162 that is fastened to a flange 164 at a distal end 166 of the cone 160 using nuts and bolts, or other suitable fastening technique, as best shown in FIG. 3. In some embodiments, the cone 160 tapers from a diameter that is larger than the diameter 144 of the fan 116 to the diameter 146 of the tubular body 112. In some embodiments, a finger cage 168 covers an opening 170 at a proximal end 172 of the cone 160, as shown in FIGS. 2-7.

In some embodiments, the fan 116 is supported by a cylindrical member 174 (FIGS. 7 and 10), such as within the cylindrical member 174, that is received within the proximal end 172 of the cone. In some embodiments, mating flanges of the cylindrical member 174 and the cone 160 are secured together using nuts and bolts, or through another suitable fastening technique.

Some embodiments of the invention relate to the manner in which the air-assist flare 102, such as the flare body 106, is mounted to the pipe 126. As mentioned above, in some embodiments, at least the flare body 106 is connected to the gas feed pipe 108, such that a substantial majority of the weight of the air-assist flare 102 is supported by the pipe 108. This may be accomplished in many different ways, such as through the use of a bracket mounted to the tubular body 112 or other component of the air-assist flare 102.

In some exemplary embodiments, the gas feed pipe 108 is attached to the cone 160. In some embodiments, the distal end 120 of the gas feed pipe 108 extends into the tubular body 112 through an opening 176 in the cone 160, as shown in FIGS. 1, 3 and 10, or through an opening in the tubular body 112. In some embodiments, the gas feed pipe 108 is fed between the cylindrical member 174 and the cone 160, as shown in FIG. 10. In some embodiments, the cone 160 includes tabs 178 that facilitate the securement of the cone 160 to the gas feed pipe 108. In some embodiments, the tabs 178 are secured to the gas feed pipe 108 through welding, the use of one or more brackets, or other suitable fastening technique.

In some embodiments, the air-assist flare 102 is supported on the pipe 126 in a manner that substantially minimizes the amount of torque on the coupling 152, the pipe 108 and/or the pipe 126. In some embodiments, the main pipe 126 extends vertically from the ground 180 or other support structure, as shown in FIG. 1. In some embodiments, the longitudinal axis 114 of the flare body 106 extends vertically relative to the ground 180, as shown in FIG. 1. In some embodiments, a central axis 182 of the pipe 126 is substantially parallel (i.e., within 10 degrees) to the longitudinal axis 114 of the flare body 106. In some embodiments, the central axis 182 of the pipe 126 is substantially coaxial to the longitudinal axis 114 of the flare body 106. That is, the axis 182 is less than 4 inches, less than 2 inches, less than 1 inch, or less than 0.5 inches from the longitudinal axis 114, when measured in a plane that is perpendicular to the axes 182 and 114. In some embodiments, the longitudinal axis 114 of the flare body 106 is substantially coaxial to the axis 182, when the axis 114 extends within the circumference of the pipe 126.

In some embodiments, the longitudinal axis 114 represents a center of gravity of the flare body 106, which may or may not be aligned with the axis of the tubular body 112. In some embodiments, the air-assist flare 102 is supported in such a manner on the pipe 126 that the horizontal location of the center of gravity of the air-assist flare 102 is substantially coaxial to the central axis 182 of the pipe 126 or the coupling 152, such as being located within the circumference of the pipe 126 or coupling 152, or is located within a few inches (i.e., less than 1-4 inches) of the pipe 126 or the coupling 152.

In some embodiments, the gas feed pipe 108 extends around a side of the fan 116, and includes a section 190 that is displaced from the axis 114 and/or the axis 182, as shown in FIGS. 1 and 2. In some embodiments, this prevents interference between the gas feed pipe 108 and the fan 116. In some embodiments the section 190 includes a bend section 194 proximate the coupling 152, a straight section 196 attached to the bend section 194, a bend section 198 attached to the straight section 166, a straight section 200 attached to the bend section 198, a bend section 202 attached to the straight section 200, a straight section 204 attached to the bend section 202, a bend section 206 attached to the straight section 204, and a straight section 208 attached to the bend section 206. Other arrangements for the gas feed pipe 108 forming the displaced section 160 may also be used. In some embodiments, the straight pipe section 200 is substantially coaxially aligned with the longitudinal axis 114 of the tubular body 112. In some embodiments, the coupling 152 and/or a section of the pipe 108 that is external to the flare body 106 is substantially coaxial to the longitudinal axis 114, such as the section of pipe adjacent the coupling 152. In some embodiments, the pipe 108 is substantially aligned in a single plane.

The above-described arrangement, in which the air-assist flare is mounted vertically above the pipe 126 or the coupling 152, places a low amount of torque on the pipe 126 or the coupling 152, and simplifies the mounting of the air-assist flare 102 over prior art designs that are side-fed with combustible gas.

In some embodiments, the air-assist flare 102 can be installed at a desired height by adjusting the pipe 108. In some embodiments, the air-assist flare 102 is installed at a height of approximately 6-12 feet from grade measured to the top of the distal end 150 of the flare body 106. Additionally, the height at which the air-assist flare 102 is installed may be easily customized by simply adjusting the pipe 108. Prior art air-assist flares typically have an installed height of 20 feet or more from grade, and lack the ability to easily vary the height.

In some embodiments, the straight pipe section 208 includes at least one guide member 210 (FIG. 10), such as fins or tabs, that ensure that the straight pipe section 208 is substantially in the central region of the tubular body 112. In some embodiments, the guide members 210 assist in stifling the airflow 140 within the tubular body 112.

As mentioned above, in operation, the airflow 140 mixes with the flammable gas 124 output from the gas feed pipe 108. In some embodiments, the air-assist flare 102 includes mixing blades or a spinner 212 (FIGS. 7 and 10) inside the tubular body 112 that encourage a turbulent flow of the gas 124 to enhance the mixing of the gas 124 with the airflow 140. In some embodiments, the mixing blades 212 are located at the output port 122 of the gas feed pipe 108.

In some embodiments, the air-assist flare 102 includes a diffuser cone 214 at the distal end 150 of the flare body 106, as shown in FIGS. 1-7. In some embodiments, the diffuser cone 214 is attached to a distal end 216 of the tubular body 112, and has a diameter that expands with distance along the longitudinal axis 114 away from the tubular body 112.

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. 

What is claimed is:
 1. An air-assist flare comprising: a flare body comprising: a tubular body having a longitudinal axis; and a fan adjacent to a proximal end of the tubular body and configured to drive a flow of air through the tubular body along the longitudinal axis; and a gas feed pipe including an output port within the tubular body; and a pilot burner configured to ignite a mixture of flammable gas discharged through the output port and the flow of air; wherein the gas feed pipe supports at least a portion of the weight of the flare body.
 2. The air-assist flare according to claim 1, wherein the gas feed pipe supports at least 90% of the weight of the flare body.
 3. The air-assist flare according to claim 1, wherein the fan has a larger diameter than the tubular body.
 4. The air-assist flare according to claim 3, wherein the flare body comprises a cone surrounding the fan, the cone having a distal end attached to the proximal end of the tubular body.
 5. The air-assist flare according to claim 4, wherein the cone supports the fan.
 6. The air-assist flare according to claim 4, further comprising a finger cage attached to the cone and covering an opening at a proximal end of the cone.
 7. The air-assist flare according to claim 4, wherein the gas feed pipe extends through an opening in the cone or the tubular body.
 8. The air-assist flare according to claim 4, wherein the flare body comprises a diffuser cone attached to a distal end of the tubular body, wherein the diffuser cone has a diameter that expands with distance along the longitudinal axis away from the distal end of the tubular body.
 9. The air-assist flare according to claim 8, wherein the flare body has a length of less than 8 feet.
 10. The air-assist flare according to claim 1, further comprising mixing blades positioned adjacent the output port of the gas feed pipe, the mixing blades configured to mix flammable gas output through the output port with the flow of air.
 11. The air-assist flare according to claim 1, wherein the gas feed pipe includes a section that is external to the flare body and is displaced from the longitudinal axis.
 12. The air-assist flare according to claim 1, further comprising at least one guide member extending between the gas feed pipe and an interior wall of the tubular body, the at least one member configured to maintain a section of the gas feed pipe extending within the tubular body in substantial coaxial alignment with the longitudinal axis.
 13. The air-assist flare according to claim 1, wherein the gas feed pipe includes a section that is exterior to the flare body and is substantially coaxial to a center of gravity of the flare body.
 14. The air-assist flare according to claim 1, further comprising a sensor, wherein a speed at which the fan rotates is controlled based on a signal output from the sensor.
 15. The air-assist flare according to claim 1, wherein the flare body weighs less than 180 pounds.
 16. An air-assist flare system comprising: an air assist flare comprising: a flare body comprising: a tubular body having a longitudinal axis; and a fan adjacent to a proximal end of the tubular body and configured to drive a flow of air through the tubular body along the longitudinal axis; and a gas feed pipe including a distal end having an output port within the tubular body; and a pilot burner; a main pipe having a distal end coupled to a proximal end of the gas feed pipe; a source of waste gas coupled to the main pipe; a source of pilot gas coupled to the pilot burner; an ignition controller configured to trigger ignition of the pilot gas output through the pilot burner; and a fan controller configured to control the fan; wherein the gas feed pipe supports at least a portion of the weight of the flare body.
 17. The air-assist flare system according to claim 16, wherein the longitudinal axis extends through the main pipe.
 18. The air-assist flare system according to claim 16, wherein: the air-assist flare includes a sensor; and the fan controller controls a speed of rotation of the fan based on a signal output from the sensor.
 19. The air-assist flare system according to claim 16, wherein the flare body has a length of less than 8 feet and weighs less than 180 pounds.
 20. The air-assist flare system according to claim 16, wherein the gas feed pipe supports at least 90% of the weight of the flare body. 